How do you find maclaurin series for #sinx cosx# using maclaurin for #sinx#? Calculus Power Series Constructing a Maclaurin Series 1 Answer Cesareo R. Jul 1, 2016 #sinx cosx = sum_{k=0}^{oo}2^{2k}(-1)^k(x^{2k+1})/((2k+1)!)# Explanation: We know #sin(a+b)=sin(a)cos(b)+sin(b)cos(a)# if #a = b# #sin(2a)=2sin(a)cos(a)# then #sinx cosx = sin(2x)/2# Supposing that #sin x = sum_{k=0}^{oo}(-1)^k(x^{2k+1})/((2k+1)!)# then #sinx cosx = sum_{k=0}^{oo}2^{2k}(-1)^k(x^{2k+1})/((2k+1)!)# Answer link Related questions How do you find the Maclaurin series of #f(x)=(1-x)^-2# ? How do you find the Maclaurin series of #f(x)=cos(x^2)# ? How do you find the Maclaurin series of #f(x)=cosh(x)# ? How do you find the Maclaurin series of #f(x)=cos(x)# ? How do you find the Maclaurin series of #f(x)=e^(-2x)# ? How do you find the Maclaurin series of #f(x)=e^x# ? How do you find the Maclaurin series of #f(x)=ln(1+x)# ? How do you find the Maclaurin series of #f(x)=ln(1+x^2)# ? How do you find the Maclaurin series of #f(x)=sin(x)# ? How do you use a Maclaurin series to find the derivative of a function? See all questions in Constructing a Maclaurin Series Impact of this question 2398 views around the world You can reuse this answer Creative Commons License